1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a multi-domain vertical alignment liquid crystal display device.
2. Description of Related Art
At present, the liquid crystal displays are all developed to have optimum size, high luminance, high contrast, wide viewing angle and high color saturation. To solve the viewing angle problem widely found in the current liquid crystal displays, a multi-domain vertical alignment (MVA) is introduced. In the MVA liquid crystal display devices, the display area is divided into multiple domains so that liquid crystals are aligned in a compensatory manner. In this connection, the phase retardation values are the same, regardless of the viewing angle. Hence, no grayscale inversion phenomenon is generated. Also, the contrast is increased, and the response time is shortened.
FIG. 1(a) and FIG. 1(b) show a cross-sectional view and a top view of a conventional MVA liquid crystal display device, respectively. As shown, a first electrode 11 having a plurality of protrusions 3 disposed on the surface thereof is disposed on the surface of a first substrate 1. Pixel electrodes 4 are disposed on the surface of a second substrate 2, a plurality of first slits 5 being interposed between the pixel electrodes 4 for spacing the pixel electrodes 4 apart. Thus, liquid crystal molecules 7 in the same domain are tilted in an identical direction. In other words, the conventional MVA liquid crystal display devices have the same tilted angle in one grayscale. Even so, the liquid crystal shows display images in different grayscales by the refractive characteristic of the liquid crystals. When the angle between a sight line and the liquid crystals is changed, the light intensity sensed by the eye will be inconsistent. Therefore, when the conventional MVA liquid crystal display device is viewed (as shown in FIG. 1(a)) from different angles, the sight line and the longitudinal axis of the liquid crystals form various angles which results in a non-uniform brightness, especially at any of two adjacent display domains in the vicinity of the protrusions of the pixel electrodes of the multi-domain vertical alignment liquid crystal display device as viewed in a microcosmic state. This is because the liquid crystal molecules within these two adjacent domains tilt at different angles when a voltage is applied. When viewed, the sight line forms various angles with respect to the longitudinal axis of the liquid crystals, and thus, the two adjacent domains have non-uniform brightness. The person will therefore see the non-uniform brightness at the two adjacent domains in the vicinity of the protrusions. When such an effect expands to the whole panel display area, the panel will have non-uniform brightness and impaired display quality. Therefore a dire need exists to improve the conventional MVA liquid crystal display devices.